Nokea
The cleaning of glassware and tableware in restaurants falls into the category of
- A. degermation.
- B. sterilization.
- C. disinfection.
- D. sanitization.
Correct Answer: D
Rationale: The correct answer is D: sanitization. Sanitization is the process of reducing the number of microorganisms on surfaces to a safe level. In restaurants, cleaning glassware and tableware aims to eliminate harmful bacteria to prevent foodborne illnesses. Degermation (A) focuses on removing germs from a specific area, sterilization (B) eliminates all microorganisms, and disinfection (C) reduces the number of pathogens but may not completely eliminate them, making them less effective choices for this context.
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Which of the following best describes the function of bacterial capsules?
- A. Enhance bacterial motility
- B. Enable bacterial adherence to surfaces
- C. Prevent bacterial DNA replication
- D. Protect bacteria from desiccation
Correct Answer: B
Rationale: The correct answer is B: Enable bacterial adherence to surfaces. Bacterial capsules are a protective layer outside the cell wall that helps bacteria adhere to surfaces and evade host immune responses. This allows bacteria to colonize and infect host tissues.
A: Enhancing bacterial motility is typically associated with flagella, not capsules.
C: Bacterial DNA replication is not directly affected by capsules.
D: Bacterial capsules do play a role in protecting bacteria from desiccation by providing a barrier against drying out. However, the primary function is enabling adherence to surfaces.
The most important virulence factor of Neisseria meningitidis is:
- A. Exotoxin
- B. Polysaccharide capsule
- C. Beta-lactamase
- D. Pyrogenic toxin
Correct Answer: B
Rationale: The correct answer is B: Polysaccharide capsule. The capsule of Neisseria meningitidis is crucial for its virulence as it helps the bacteria evade the host immune system by inhibiting phagocytosis. This allows the bacteria to survive and multiply in the host, leading to invasive infections. Exotoxins, beta-lactamase, and pyrogenic toxins are not the main virulence factors of Neisseria meningitidis and do not play as significant a role in its pathogenicity as the polysaccharide capsule.
Gram-positive cocci arranged in chains were found in a wound smear. The bacteria were catalase-negative and beta-hemolytic on blood agar. What is the causative agent?
- A. Streptococcus pyogenes
- B. Staphylococcus aureus
- C. Enterococcus faecalis
- D. Micrococcus luteus
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pyogenes. This bacterium fits all the given characteristics: Gram-positive cocci arranged in chains, catalase-negative, and beta-hemolytic on blood agar. Streptococcus pyogenes is known for causing skin and soft tissue infections. Staphylococcus aureus (B) is catalase-positive and typically forms clusters, not chains. Enterococcus faecalis (C) is catalase-negative but not beta-hemolytic. Micrococcus luteus (D) is catalase-positive and not typically associated with wound infections.
How the prepared immunofluorescence slide should be examined?
- A. Under the fluorescence microscope using x100 oil immersion objective
- B. Under light microscope using x100 oil immersion objective
- C. Using electron microscopy
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because immunofluorescence slides are examined under a fluorescence microscope with a x100 oil immersion objective. This is because immunofluorescence relies on the detection of fluorescently labeled antibodies, which emit light when excited by a specific wavelength. Using a fluorescence microscope allows for visualization of these labeled antibodies at high magnification and resolution, enabling precise examination of cellular structures and protein localization. Choice B is incorrect as light microscopes are not suitable for visualizing fluorescence. Choice C is incorrect as electron microscopes use electrons, not light, for imaging, which is not compatible with immunofluorescence. Choice D is incorrect as there is a specific method for examining immunofluorescence slides.
While studying the pneumonic infection in 1928 the English doctor Frederick Griffith discovered:
- A. Translation
- B. Transformation
- C. Transcription
- D. Conjugation
Correct Answer: B
Rationale: The correct answer is B: Transformation. Frederick Griffith discovered bacterial transformation, where genetic material can be transferred between bacteria. He observed this phenomenon while studying pneumonia-causing bacteria in 1928. Transformation is the process by which bacteria take up external DNA and incorporate it into their own genome. This discovery was crucial in understanding how genetic information can be transferred between organisms.
Rationale for other choices:
A: Translation - This term refers to the process of protein synthesis from mRNA, not relevant to Griffith's discovery.
C: Transcription - This term refers to the process of synthesizing RNA from DNA, not related to Griffith's discovery.
D: Conjugation - This term refers to the direct transfer of genetic material between bacterial cells through cell-to-cell contact, which is different from the phenomenon Griffith observed.